Abstract: A slide-plate filter apparatus particularly for plastic stock under pressure in which rigid filter plate sections carrying corresponding sections of filter media are fed in a continuing sequence across the flow path of the plastic stock is provided with off-set retainer plates for directing plastic stock which is forced between the filter plate sections into a path which includes filter media, so that no unfiltered plastic stock can pass through the apparatus.

Abstract: A slide filter device for filtering thermoplastic and other materials which become fluid or stiffen in response to temperature change, having rigid self-supporting slide plate means movable within a housing from an inlet port passageway to an outlet port passageway for supporting and carrying replaceable filter media across the path of fluid flow (i.e.: the "melt stream") of the working material. The outlet port passageway is larger in cross-section than the slide plate means and a seal of stiffened working material is formed in the gap between the slide plate means and the walls of the passageway. Seal material emerges from the outlet port passageway affixed to the slide plate means as the slide plate means is advanced across the melt stream.